How do I generate a unique numbered PDF each time I generate or print a report.

I've noticed that the Caption on the form can be changed, but can it be autonumbered based on a unique field followed by another unique number.

I know how to print the report to a PDF, but this also applies to other software.

I basically want to be able to click the print button on the computer (and print to the default PDF printer), but have the PDF file with a unique number code, etc and then stored.